This invention relates to mirrors for vehicles and other purposes and, more particularly, to electro-optic mirrors incorporating an electro-optic medium or cell which varies the transmittance of light upon the application of an electric field and a perimeter which conceals any seal structure and electrical connections, and/or enhances electrical conductivity for increased coloration performance, and/or provides an appealing border around the mirror.
In the past, vehicular rearview mirror designers have had a wide choice of mirror case bezels for holding interior and exterior rearview mirrors on vehicles. Typically, mirror cases have included an edge bezel or retaining rim which extends around the periphery of the mirror element and over the viewing surface of the mirror, typically to a width of 5 millimeters or so. More recently, however, vehicle designers have desired thinner, less noticeable bezels. One reason for this is the aesthetic or cosmetic appeal of thin bezels since thick bezels are judged, from a styling viewpoint, to be heavy or chunky and to detract from the visual appeal of the mirror design.
Another reason applies to outside or exterior vehicle mirrors where bezel design, and the desire to have the bezel as thin as possible, is particularly important. Minimization of the aerodynamic drag caused by outside mirror case assemblies leads to a desire to utilize as small a mirror reflector element as comfortably meets the need to provide a sufficiently wide field of view to the driver. Such mirrors provide the driver with confidence and comfort in using the outside rearview mirror for critical driving decisions such as lane changes and the like. Also, for outside mirrors, a sufficient reflector area must be available to satisfy the field of view requirements as set forth in the U.S. Federal Motor Vehicle Standard No. 111. For a typical driver-side outside rearview mirror used in the United States, field of view is reduced by about 2% for every 1 millimeter of shrinkage in overall dimensions. Many outside mirrors in current use utilize no bezels and automaker stylists, and thus consumer tastes, have grown accustomed to, and appreciative of, small bezels or no bezels on automotive outside mirrors. Indeed, it has been customary in many outside/exterior rearview mirrors to avoid the use of any bezel by mounting the mirror element directly on a backing plate with adhesives or the like.
More recently, electro-optic mirrors have required larger, thicker bezels because of the very nature of the mirror assembly. Such mirrors typically include a pair of glass substrates spaced from one another and retained together by epoxy seals forming a cavity therebetween which retains liquid crystal, electrochromic or electrochemichromic media which darkens or dims when electricity is applied across the media. In such constructions, bus bars extend beyond the seal structure from edges of the glass substrates to provide attachment points for electrical leads. In order to effectively hide these seal and bus bar regions in a conventional electro-optic mirror, the bezel or retaining rim at the perimeter of the mirror assembly was required to be significantly wider than for conventional rearview mirrors, i.e., a width of 6 to 7 millimeters or so. Consequently, the desire for small bezels could not be met in these mirror assemblies.
Because of their expense, electro-optic rearview mirrors, especially for the outside of a vehicle, may not be installed on all vehicles and, in many cases, are considered an optional item. Even when installed, such mirrors may be placed only on the driver's side. However, in their desire for symmetry on a vehicle, vehicle designers feel restricted by the size of the required bezels necessary to hide the electro-optic seal and electrical structure of such mirrors. This is because a large bezel, even on a conventional exterior mirror, would be necessary to provide symmetry on a vehicle including only a single electro-optic exterior mirror, i.e., a similar appearance on both sides of the vehicle.
Therefore, a need has arisen in the automotive industry for rearview mirrors, and especially electro-optic rearview mirrors, which avoid the necessity of large retaining bezels or rims as are currently required on conventional electro-optic mirrors. Concurrently, the advantages of enhanced coloration performance, reduced aerodynamic drag, increased field of view in the mirror for a given small bezel size, and improved aesthetic appeal have also been desired. The present invention was conceived in recognition of and as a solution for these needs.